Ciprofloxacin - How It Works
Clinical pharmacology details from the US FDA-approved label: how Ciprofloxacin works in your body, how it's absorbed, how long it stays active, and how it's eliminated.
Mechanism of Action
1 2 .1 Mechanism of Action Ciprofloxacin is a member of the fluoroquinolone class of antibacterial agents [see Microbiology ].
1 2 CLINICAL PHARMACOLOGY 1 2 .1 Mechanism of Action Ciprofloxacin is a member of the fluoroquinolone class of antibacterial agents [see Microbiology ].
3 Pharmacokinetics Absorption The absolute bioavailability of ciprofloxacin when given as an oral tablet is approximately 70% with no substantial loss by first pass metabolism.
Ciprofloxacin maximum serum concentrations (C max ) and area under the curve (AUC) are shown in the chart for the 250 mg to 1000 mg dose range (Table 12).
Table 12: Ciprofloxacin Cmax and AUC Following Administration of Single Doses of Ciprofloxacin Tablets to Healthy Subjects Dose (mg) Cmax (mcg/mL) AUC (mcg•hr/mL) 250 1.2 4.8 500 2.4 11.6 750 4.3 20.2 1000 5.4 30.8 Maximum serum concentrations are attained 1 to 2 hours after oral dosing.
Mean concentrations 12 hours after dosing with 250, 500, or 750 mg are 0.1, 0.2, and 0.4 mcg/mL, respectively.
The serum elimination half-life in subjects with normal renal function is approximately 4 hours.
Serum concentrations increase proportionately with doses up to 1000 mg.
A 500 mg oral dose given every 12 hours has been shown to produce an AUC equivalent to that produced by an intravenous infusion of 400 mg ciprofloxacin given over 60 minutes every 12 hours.
A 750 mg oral dose given every 12 hours has been shown to produce an AUC at steady-state equivalent to that produced by an intravenous infusion of 400 mg given over 60 minutes every 8 hours.
A 750 mg oral dose results in a C max similar to that observed with a 400 mg intravenous dose (Table 13).
A 250 mg oral dose given every 12 hours produces an AUC equivalent to that produced by an infusion of 200 mg ciprofloxacin given every 12 hours.
Table 13: Steady-state Pharmacokinetic Parameters Following Multiple Oral and Intravenous Doses (Adults) P a r a m e t e rs 500 mg 400 mg 750 mg 400 mg every 12 hours, orally every 12 hours, intravenously every 12 hours, orally every 8 hours, intravenously AUC 0-24h,ss (μg•h/mL) 27.4 * 25.4 * 31.6 * 32.9 ** C max,ss (μg/mL) 2.97 4.56 3.59 4.07 *:AUC 0–12h x 2 **:AUC 0-8h x 3 Food When ciprofloxacin tablets are given concomitantly with food, there is a delay in the absorption of the drug, resulting in peak concentrations that occur closer to 2 hours after dosing rather than 1 hour.
The overall absorption of ciprofloxacin tablets, however, is not substantially affected.
Avoid concomitant administration of ciprofloxacin tablets with dairy products (like milk or yogurt) or calcium-fortified juices alone since decreased absorption is possible; however, ciprofloxacin tablets may be taken with a meal that contains these products.
Distribution The binding of ciprofloxacin to serum proteins is 20% to 40% which is not likely to be high enough to cause significant protein binding interactions with other drugs.
After oral administration, ciprofloxacin is widely distributed throughout the body.
Tissue concentrations often exceed serum concentrations in both men and women, particularly in genital tissue including the prostate.
Ciprofloxacin is present in active form in the saliva, nasal and bronchial secretions, mucosa of the sinuses, sputum, skin blister fluid, lymph, peritoneal fluid, bile, and prostatic secretions.
Ciprofloxacin has also been detected in lung, skin, fat, muscle, cartilage, and bone.
The drug diffuses into the cerebrospinal fluid (CSF); however, CSF concentrations are generally less than 10% of peak serum concentrations.
Pharmacokinetics
1 2 . 3 Pharmacokinetics Absorption The absolute bioavailability of ciprofloxacin when given as an oral tablet is approximately 70% with no substantial loss by first pass metabolism. Ciprofloxacin maximum serum concentrations (C max ) and area under the curve (AUC) are shown in the chart for the 250 mg to 1000 mg dose range (Table 12). Table 12: Ciprofloxacin Cmax and AUC Following Administration of Single Doses of Ciprofloxacin Tablets to Healthy Subjects Dose (mg) Cmax (mcg/mL) AUC (mcg•hr/mL) 250 1.2 4.8 500 2.4 11.6 750 4.3 20.2 1000 5.4 30.8 Maximum serum concentrations are attained 1 to 2 hours after oral dosing. Mean concentrations 12 hours after dosing with 250, 500, or 750 mg are 0.1, 0.2, and 0.4 mcg/mL, respectively. The serum elimination half-life in subjects with normal renal function is approximately 4 hours. Serum concentrations increase proportionately with doses up to 1000 mg. A 500 mg oral dose given every 12 hours has been shown to produce an AUC equivalent to that produced by an intravenous infusion of 400 mg ciprofloxacin given over 60 minutes every 12 hours. A 750 mg oral dose given every 12 hours has been shown to produce an AUC at steady-state equivalent to that produced by an intravenous infusion of 400 mg given over 60 minutes every 8 hours. A 750 mg oral dose results in a C max similar to that observed with a 400 mg intravenous dose (Table 13). A 250 mg oral dose given every 12 hours produces an AUC equivalent to that produced by an infusion of 200